Greetings. I've been tasked with trying to find guidance within ITIL on how best to structure maintenance windows for our managed hosting operation. All I've learned thus far is that ITIL recommends that maintenance windows be a part of the change management process, but should they be product based or grouped along with lines of business?

Apparently, some of our customers dont like that fact that our SLA's are not enforced during our established maintenance windows and our COO is looking for some ITIL way to justify this.

We all know that ITIL is very high level and so I don't expect to find step by step instructions, but thus far I haven't been able to find ANYTHING that I can take back to my management team except to say, "No, this doesnt exist".

There is something singularly illogical here. First I will assume that by "enforced" you mean "necessarily met".

But that does not scratch the surface. If you have agreed a service level for a period of time, then that is what you have agreed. Your customer(s) have you over a barrel if you cannot meet the agreement.

Who calculated your service capability without taking into account the necessity of taking reducing services for the performance of necessary maintenance?

As I see it you have a choice between investing in sufficient infrastructure to hold levels of service even during maintenance or renegotiate your SLA.

If you are contracting (even in the loosest sense) to deliver a service then you need to agree the duration, frequency and time-windows for any work that reduces the service levels from those otherwise agreed.

The fact that maintenance activity has at least a potential for involving changes is a bit of a red herring.

Now for the really bad news. It's not just, as John said, that ITIL does not provide guidance at this level.

No. No. No.

Since ITIL is guidance, and only guidance, it does not contain the authority to justify anything. Ever.

You can never say "this is correct and that is incorrect because ITIL says so". You can merely say "ITIL suggests this approach"._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718

While ITIL does not address Scheduled Maintenance Windows specifically it does promote a scheduled Change and Release window..

."Pre-agreed and established change and release windows help an organization improve the planning and throughput of changes and releases. For example a release window in a maintenance period of one hour each week may be sufficient in install minor releases only. Major releases may need to be scheduled with the business and stakeholders at a pre-determined time
[/quote]

I think there should be a clear understanding about maintenance windows.
I realized that people often associate maintenance windows with change and release, while they are not directly related (at least in my understanding).
Maintenance window is a slot (agreed by related parties) where it is safe to bring down a system to do maintenance. It does not necessary mean that there will be any change or release. However, changes and release would usually find any maintenance windows as the safest time slot for deployment.
I agree with Viking, in my experience, there is no specific guidance for maintenance windows. In fact, this is something tricky that should involve, provider, customer and supplier.
For example, 24-hour transaction base systems would hardly find time slot for maintenance than batch or non-transaction based system

Apparently, some of our customers dont like that fact that our SLA's are not enforced during our established maintenance windows and our COO is looking for some ITIL way to justify this.
Anybody, anybody...Bueller?

Kingtubby - Would be interested to know what level of system availability you have agreed with your customers.

By now, you have got an answer on what maintanance window is and what is ijn ITIL for it..

Now operationally speaking, Maintatance windows alighned to business lines works better for all application related areas... ifyour organization is global then need to explicitly define the maintatance window for each region as the impact would be different

Per your maintatance window, you should be able to formulate your release calander so that both is in sync....

there would already be a maintatance window scheduled by few business lines... design one so as to make less disturbance in the current system....

Try having a specific maintanance window (approx 2 weekends) for infra every month considering the frequency of changes which need the maintanance window...

Don't dig deep into ITIL for maintatance window - because it seriously is an operational decision on how to have them and change management looks at this a good practise to have them for sure

The Change management policy,the Service level management process, the Change Board policy ,The fact that maintenance activity has at least a potential for involving changes is a bit of a red herring.Maintenance window is a slot (agreed by related parties) where it is safe to bring down a system to do maintenance. It does not necessary mean that there will be any change or release.

And as such it needs to be articulated in appropriate SLAs rather than treated as an exception to the SLA